Microsoft has in a landmark case challenged in U.S. federal court a search warrant for private email communications located in the company's facility in Dublin, Ireland, after a magistrate judge quashed in April its opposition to the warrant.

The company like many others in the technology industry are concerned that the U.S. government's demands for data held abroad could spook customers abroad from their cloud and other services.

Verizon Communications has filed a brief Tuesday supporting Microsoft's petition, and other companies are expected to follow, according to The New York Times.

Verizon believes that the magistrate judge's decision to allow a search warrant for the email was wrong, since U.S. law does not allow the government to issue search warrants to obtain customer data stored overseas, according to the company's general counsel, Randal S. Milch, in an emailed statement.

Verizon has not received and does not expect any demands for customers' data stored in data centers outside the U.S., the statement said. The company filed the brief "to try to avoid any unnecessary confusion or concern on behalf of customers outside the U.S. who store their data in cloud data centers outside the U.S.," Milch added.

The company warned in its filing that if the warrant is enforced, it would violate international agreements, harm U.S business, subject Americans to potential liability abroad, and invite foreign governments to unilaterally obtain electronic communications and data of Americans in the U.S.

In a redacted filing in the U.S. District Court for the Southern District of New York, Microsoft has objected to a warrant issued by a magistrate judge under the Electronic Communications Privacy Act, as it purports to authorize the U.S. government to search "any and all" of Microsoft's facilities worldwide.

The private email communications that the government seeks are stored in a server in Dublin and the U.S. Congress has not authorized the issuance of warrants that reach outside U.S. territory, Microsoft wrote in the filing.

U.S. Magistrate Judge James C. Francis IV of the New York court had in April refused to quash a December warrant that authorized the search and seizure of information, including content and identifiers such as name and physical address, associated with a specified Web-based email account stored at Microsoft's premises.

Microsoft complied with the search warrant by providing non-content information held on its U.S. servers but after it determined that the account was hosted in Dublin and the account content also stored there, it filed to quash the warrant as it requires that information held abroad to be produced, according to the magistrate judge's order.

If the territorial restrictions on conventional warrants applied to warrants issued under section 2703 (a) of the Stored Communications Act, the burden on the Government would be substantial, and law enforcement efforts would be seriously impeded, the magistrate judge wrote in his order. The statute covers required disclosure of wire or electronic communications in electronic storage.

Microsoft has been demanding reform of surveillance by the U.S. National Security Agency, stating that it is affecting its business abroad. The company's General Counsel Brad Smith wrote last week that Microsoft was concerned about government attempts to use search warrants to force companies to turn over contents of communications of non-U.S. customers that are stored exclusively outside the country. The surveillance had resulted in hesitation around the world over the adoption of technologies like cloud computing, he added.

Cisco Systems' CEO John Chambers also wrote last month to U.S. President Barack Obama, asking him to intervene so that U.S technology sales were not hit by a loss of trust from customers abroad.

Microsoft said in its filing in the New York court that the company has met with increasing concerns from both current and potential customers abroad about the "U.S. government's extra-territorial access to their user information." Allowing warrants issued under the ECPA would violate international laws and treaties and "reduce the privacy protection of everyone on the planet."

John Ribeiro covers outsourcing and general technology breaking news from India for The IDG News Service. Follow John on Twitter at @Johnribeiro. John's e-mail address is john_ribeiro@idg.com